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smmu(4): don't always set DMA coherent tag
Le Wed, Aug 27, 2025 at 02:03:39PM +0200, Patrick Wildt a écrit : > Hi, > > SMMUs don't necessarily influence device DMA coherency attributes. > I assume we have been lucky so far that our machines that have an > SMMUv2 usually have devices with DMA coherency. On the RK3588 > this is not the case, and us always adding the COHERENT flag makes > devices fail to work when used with smmu(4) enabled. > > Please give this a run on machines where "dmesg | grep ^smmu" shows > some output. i dont have regressions on the omnibook x14 with that patch and the previous, but smmu is still disabled. should i test with it enabled ? that's only adding 'early 1' to the 'smmu* at fdt?' line right ?
smmu(4): don't always set DMA coherent tag